Purpose: An important assumption in dosimetry prior to radionuclide therapy is the equivalence of pretherapeutic and therapeutic biodistribution. In this study the authors investigate if this assumption is justified in sst2‐receptor targeting peptide therapy, as unequal amounts of peptide and different peptides for pretherapeutic measurements and therapy are commonly used. Methods: Physiologically based pharmacokinetic models were developed. Gamma camera and serum measurements of ten patients with metastasizing neuroendocrine tumors were conducted using111In‐DTPAOC. The most suitable model was selected using the corrected Akaike information criterion. Based on that model and the estimated individual parameters, predicted and measured 90Y‐DOTATATE excretions during therapy were compared. The residence times for the pretherapeutic (measured) and therapeutic scenarios (simulated) were calculated. Results: Predicted and measured therapeutic excretion differed in three patients by 10%, 31%, and 7%. The measured pretherapeutic and therapeutic excretion differed by 53%, 56%, and 52%. The simulated therapeutic residence times of kidney and tumor were 3.1 ± 0.6 and 2.5 ± 1.2 fold higher than the measured pretherapeutic ones. Conclusions: To avoid the introduction of unnecessary inaccuracy in dosimetry, using the same substance along with the same amount for pretherapeutic measurements and therapy is recommended.

The aim of this work is to build up a common framework for a class of discriminative training criteria and optimization methods for continuous speech recognition. A uni®ed discriminative criterion based on likelihood ratios of correct and competing models with optional smoothing is presented. The uni®ed criterion leads to particular criteria through the choice of competing word sequences and the choice of smoothing. Analytic and experimental comparisons are presented for both the maximum mutual information (MMI) and the minimum classi®cation error (MCE) criterion together with the optimization methods gradient descent (GD) and extended Baum (EB) algorithm. A tree search-based restricted recognition method using word graphs is presented, so as to reduce the computational complexity of large vocabulary discriminative training. Moreover, for MCE training, a method using word graphs for e cient calculation of discriminative statistics is introduced. Experiments were performed for continuous speech recognition using the ARPA wall street journal (WSJ) corpus with a vocabulary of 5k words and for the recognition of continuously spoken digit strings using both the TI digit string corpus for American English digits, and the SieTill corpus for telephone line recorded German digits. For the MMI criterion, neither analytical nor experimental results do indicate signi®cant di erences between EB and GD optimization. For acoustic models of low complexity, MCE training gave signi®cantly better results than MMI training. The recognition results for large vocabulary MMI training on the WSJ corpus show a signi®cant dependence on the context length of the language model used for training. Best results were obtained using a unigram language model for MMI training. No signi®cant correlation has been observed between the language models chosen for training and recognition. Ó 2001 Elsevier Science B.V. All rights reserved. ZusammenfassungZiel dieser Arbeit ist die Scha ung eines einheitlichen Rahmens fur eine Klasse von diskriminativen Trainingskriterien und Optimierungsmethoden fur die kontinuierliche Spracherkennung. Dazu wird ein einheitliches Kriterium de®niert, das auf Wahrscheinlichkeitsverhaltnissen von korrekten und konkurrierenden Modellen basiert. Spezielle Kriterien ergeben sich daraus durch die Wahl der konkurrierenden Wortfolgen sowie der Glattung. Fur die Kriterien maximum mutual information (MMI) und minimum classi®cation error (MCE), sowie deren Optimierung mittels Gradientenabstieg (GD) und erweitertem Baum ( ResumeLe but de ce travail est de de®nir un cadre commun incluant un ensemble de criteres d'apprentissage discriminant et de methodes d'optimisation pour la reconnaissance de la parole continue. Nous introduisons un critere discriminant fonde sur le rapport entre la vraissemblance des modeles corrects et concurrents. Ce critere general conduit a de®nir des criteres speci®ques par le choix des sequences de mots en concurrence et par celui de la methode de lissage. Des comparaisons analytiques et experiment...

Individualized treatment planning is needed in the investigated patient group. The use of a PBPK model and the inclusion of patient specific data, e.g., weight, tumor volume, and glomerular filtration rate, do not suffice to predict the therapeutic biodistribution. Integrating all available a priori information in the PBPK model and using additionally PET data measured at one time point for tumor, kidneys, spleen, and liver could possibly be sufficient to perform an individualized treatment planning.

Tinnitus describes the subjective perception of a sound despite the absence of external stimulation. Being a sensory symptom the majority of studies focusses on the auditory pathway. In the recent years, a series of studies suggested a crucial involvement of the limbic system in the manifestation and development of chronic tinnitus. Regarding cognitive symptoms, several reviews addressed the presence of cognitive impairments in tinnitus as well and concluded that attention and memory processes are affected. Despite the importance for social communication and the reliance on a highly functional auditory system, speech comprehension remains a largely neglected field in tinnitus research. This is why we review here the existing literature on speech and language functions in tinnitus patients. Reviewed studies suggest that speech comprehension is impaired in patients with tinnitus, especially in the presence of competing noise. This is even the case in tinnitus patients with normal hearing thresholds. Additionally, speech comprehension measures seem independent of other measures such as tinnitus severity and perceived tinnitus loudness. According to the majority of authors, the speech comprehension difficulties arise as a result of central processes or dysfunctional neuroplasticity.

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